Troubleshooting non running LT1

[GVMV]

I had another post but it's pretty long and now going to condense into one post.

I was driving down the freeway and car sputtered and just died.

No engine codes now or check engine light before it died.

I have replaced Ignition Coil and Ignition Control Module. I have the correct voltages at pins at the
ICM.

I have checked for spark on spark plugs #1 and #4 and have spark at both locations.(tested using old big screwdriver in boot method)

I have 40# of fuel pressure at the rail and the Injectors are firing (tested using a fuel pressure gauge and noid light set)

It still will not run or even start.

I am going to pull a valve cover off and confirm valves are moving to removed possibility of mechanical failure.

I would guess if valves are moving then next step is to replace Optispark.

Does anyone concur?

Vince

[IronOutlaw]

I'm not one to tell someone to throw parts at a car but more than likely it's the opti. Your probably getting a sporadic spark. If the opti has alot of miles it could at least use a cap and rotor anyways.

I know you said your getting fuel but I'd still pull a plug and make sure it's getting some fuel on it after turning the engine over some.

[Chris]

I'm not one to tell someone to throw parts at a car but more than likely it's the opti. Your probably getting a sporadic spark. If the opti has alot of miles it could at least use a cap and rotor anyways.

I know you said your getting fuel but I'd still pull a plug and make sure it's getting some fuel on it after turning the engine over some.


I concur on both counts. You may have flooded the engine with fuel as well.

[95zsean]

Here's another one to try, The Ignition switch's are known to go bad in these cars and stop them from running. Does it feel stiff when you turn the key to start the car, or do the dash lights and gauges go out when you turn the key to the point when the starter should ingage? If both or one happens it's the ignition switch.

[GVMV]

I'm not one to tell someone to throw parts at a car but more than likely it's the opti. Your probably getting a sporadic spark. If the opti has alot of miles it could at least use a cap and rotor anyways.

I know you said your getting fuel but I'd still pull a plug and make sure it's getting some fuel on it after turning the engine over some.

I can smell fuel out the exhaust after I try starting it, and plug had fuel on it when I pulled it to check it and make sure wasn't a plug issue. I don't really want to throw parts at it either but with all that I have tested don't have much choice.



I concur on both counts. You may have flooded the engine with fuel as well.

After trying to start it a few times I would try starting it with the pedal pressed to the floor, flooding is not the issue, thanks for the input tho'


Here's another one to try, The Ignition switch's are known to go bad in these cars and stop them from running. Does it feel stiff when you turn the key to start the car, or do the dash lights and gauges go out when you turn the key to the point when the starter should ingage? If both or one happens it's the ignition switch.

As you can notice from the various things I have tried, I am getting the voltage I need everywhere, I am getting fuel pressure, spark and injector pulse, so not a ignition switch issue. Thanks for the input tho'

[95LT1Z28]

Almost everything you posted was the same stuff that happened when my opti crapped out.

[95zsean]

"As you can notice from the various things I have tried, I am getting the voltage I need everywhere, I am getting fuel pressure, spark and injector pulse, so not a ignition switch issue. Thanks for the input tho'[/QUOTE]"

When my switch went bad I had all the right voltages too, but when you turn the key to start the car the last set of points to make in the switch where burnt and would not let the signal go to the ecu to let it know you where trying to start the car. My car would even start some times and only run on a few cylinders. Good Luck.

[GVMV]

"When my switch went bad I had all the right voltages too, but when you turn the key to start the car the last set of points to make in the switch where burnt and would not let the signal go to the ecu to let it know you where trying to start the car. My car would even start some times and only run on a few cylinders. Good Luck"

Interesting, I wouldn't think if the ECM doesn't know your are trying to start the car would enrich to start it, I am getting a enrichment injector pulse on trying to start and then a normal injector pulse after that. I wouldn't think the ECM would send a injector pulse if it didn't have the signal that you were starting or running. I will keep it under advisement. I am not having any other electrical issues at all.